When a television camera, or an analogous sensor, employing sequential interlaced field raster format is driven in azimuth to detect the light energy representative of a panoramic scene, the sensing of sequential interlaced fields representing any single selected frame is delayed relative to each other because of the azimuthal movement necessary to provide the panoramic scene.
Frequently, such panoramic detected scenes are desired to be recorded for further analysis at a later time.
For example, an underwater vessel, such as a submarine may use an imaging sensor extended above the surface of the sea to provide a panoramic above-water scene, recording the sensed light energy data representative of the panoramic scene, and then retracting the sensor to an underwater position.
The light energy data representative of the panoramic scene (as generated in sequential interlaced field raster format) is recorded and stored in its sequential order. For purposes of analysis of any selected portion of the recorded light energy data, a selected recorded frame of such data may be retrieved and played back on a compatible visual display means, such as a television type monitor, for example.
However, a problem arises in the visual presentation of a selected frame of the recorded light energy data representative of a portion of the panoramic scene because of the delay between the sensing of the two interlaced fields comprising any selected frame of such data, due to the fact that the sensor was panoramically driven in azimuth during the period when the scene was detected.
Thus, if the two sequential interlaced fields comprising a selected frame are retrieved from a recording means, such as a magnetically recording disc, for example, and impressed upon visual display means such as a television type monitor, without modification, the visual result will be the selected frame comprised of two fields which appear to be out of synchronism and present an appearance of "jitter" because one interlaced field is displaced horizontally relative to the other. The "jitter" is caused by the delay introduced between the sensing and recording of the two interlaced fields due to the sensor being panoramically driven in azimuth during the time of such sensing and recording.
In the present state of the art there are "stop-action" recording devices in systems presently available which attempt to circumvent the "jitter" problem by disregarding either the first or the second field of a selected frame of light energy data to provide a playback frame of visual display comprised entirely of either the first or the second field interlaced with itself. This expedient, in effect, discards one of the two interlaced fields so as to eliminate the time delay between the two interlaced fields of the selected frame of visual information. Although this technique solves the "jitter" problems, those skilled and knowledgeable in the pertinent arts will readily appreciate that in discarding one of the two interlaced fields, one half of the resolution of the visual presentation is also discarded. Since the purpose of the playback of recorded informaton of this kind is generally to achieve greater depth of analysis of visual information which may be present in a selected frame of a panoramic scene, it is obvious that discarding one half the resolution through the technique of interlacing a single frame with itself has the effect of commensurately downgrading the results of such analysis.
Accordingly, it is highly desirable that a "stop-action" playback system be devised for displaying a selected image from light energy data representative of a panoramic scene generated in sequential interlaced field raster format by a sensor driven in azimuth, which will eliminate the "jitter" otherwise encountered and yet retain maximum resolution of information contained in the light energy data.